(declare-fun a () String)
(declare-fun b () String)
(assert (str.in_re a (re.range "a" "c")))
(assert (str.in_re a (re.* (re.union (re.++ (re.union (str.to_re "a") (str.to_re "b")) (str.to_re "a")) (str.to_re (str.from_int (str.len b)))))))
(check-sat)
